<?php
// +----------------------------------------------------------------------
// | ThinkPHP [ WE CAN DO IT JUST THINK ]
// +----------------------------------------------------------------------
// | Copyright (c) 2006-2016 http://thinkphp.cn All rights reserved.
// +----------------------------------------------------------------------
// | Licensed ( http://www.apache.org/licenses/LICENSE-2.0 )
// +----------------------------------------------------------------------
// | Author: 流年 <liu21st@gmail.com>
// +----------------------------------------------------------------------

// 应用公共文件

// php截取多余字符用省略号代替
function cut_str($sourcestr,$cutlength)
{
	$returnstr = "";
	$i=0;
	$n=0;
    $str_length=strlen($sourcestr);//字符串的字节数
    while (($n<$cutlength) and ($i<=$str_length)){
	   	$temp_str=substr($sourcestr, $i, 1);
	    $ascnum=Ord($temp_str);//得到字符串中第$i位字符的ascii码
	    if ($ascnum>=224) {    //如果ASCII位高与224，
			$returnstr=$returnstr.substr($sourcestr, $i, 3); //根据UTF-8编码规范，将3个连续的字符计为单个字符        
	        $i=$i+3;            //实际Byte计为3
	        $n++;            //字串长度计1
	     } elseif ($ascnum>=192) {//如果ASCII位高与192，
	        $returnstr=$returnstr.substr($sourcestr, $i, 2); //根据UTF-8编码规范，将2个连续的字符计为单个字符
	        $i=$i+2;            //实际Byte计为2
	        $n++;            //字串长度计1
	     } elseif ($ascnum>=65 && $ascnum<=90) {//如果是大写字母，
	      	$returnstr=$returnstr.substr($sourcestr, $i, 1);
	        $i=$i+1;            //实际的Byte数仍计1个
	        $n++;            //但考虑整体美观，大写字母计成一个高位字符
	    } else {//其他情况下，包括小写字母和半角标点符号，
	      	$returnstr=$returnstr.substr($sourcestr, $i, 1);
	        $i=$i+1;            //实际的Byte数计1个
	        $n=$n+0.5;        //小写字母和半角标点等与半个高位字符宽…
	    }
 	}
    if ($str_length>$i){
        $returnstr = $returnstr . "…";//超过长度时在尾处加上省略号
    }
    return $returnstr;
  }